Purification of detergent alkylates



United States Patent 3,504,049 PURIFICATION OF DETERGENT ALKYLATES William A. Wentworth, Ponca City, Okla, assignor to Continental OilCompany, Ponca City, Okla, a corporation of Delaware No Drawing. Filed Sept. 12, 1968, Ser. No. 759,491 Int. Cl. C07c 139/14, 7/00, 25/00 US. Cl. 260-674 Claims ABSTRACT OF THE DISCLOSURE Hydrocarbon compounds having the general formula C H where n is an integer from about 10 to 24, are removed from detergent alkylates by selectively halogenating the C H type hydrocarbon compounds present in the detergent alkylate. The halogenated C H type hydrocarbon compounds can then be separated from the deter ent alkylate.

BACKGROUND OF THE INVENTION This invention relates to the detergent alkylates. In one aspect this invention relates to a method of selectively removing certain hydrocarbon compound impurities from detergent alkylates.

In another aspect it relates to a method of selectively removing hydrocarbon compounds having the general formula C H where n is an integer from 10 to 24, from detergent alkylates.

DESCRIPTION OF THE PRIOR ART It is well known to prepare highly effective, watersoluble surfactants by sulfonating the detergent alkylate obtained by alkylating an aromatic compound, usually benzene, with n-chloroparaflins having about 12 to 15 carbon atoms, in the presence of a catalyst, usually aluminum chloride. However, due to the presence of dichloride constituents in the n-chloroparafiins, hydrocarbon compounds represented by the general formula C H Where n is an integer from 10 to 24, are produced during the alkylation step of the reaction. The art has become very advanced in the preparation of detergent alkylates, particularly with respect to the sulfonation of the detergent alkylates to prepare surfactants which approach whiteness in color. While the presence of the C H hydrocarbon compounds defined above have no discernible effect upon the surface active properties of the surfactants, nevertheless, good color for these products has become a prime requirement on the part of the manufacturer or formulator of the detergent composition in which these surfactants are prevalently employed.

The manufacturers of detergent alkylates have tolerated the presence of the C H hydrocarbon compounds, such as 1,2,3,4-tetrahydronaphthalenes, 2,3-dihydroindenes, and phenyl substituted olefins, because of the difficulty required in separating these compounds from the detergent alkylate Without the expense of sacrificing undesirable amounts of the detergent alkylate. Further, due to the close boiling points and the like of the C H hydrocarbon compounds with the detergent alkylates and the extensive distillation necessary in order to effectively separate the compounds from the detergent alkylate, it is not feasible to remove the 1,2,3,4-tetrahydronaphthalenes, the 2,3-dihydroindenes, and the phenyl substituted olefins from the detergent alkylate in this manner. Consequently, the detergent alkylates utilized in the industry contain the C H hydrocarbon compounds, which could be classified as impurities.

SUMMARY OF THE INVENTION The present invention, therefore, resides in the method for selectively removing hydrocarbon compounds having "ice the general formula C H where n is an integer from 10 to 24, from detergent alkylate products prepared by an aluminum halide, such as aluminum chloride or aluminum bromide, catalyzed condensation of a partially chlorinated n-parafiin having about 12 to 15 carbon atoms with an aryl compound, such as benzene. Specifically, this method basically involves the following sequential steps:

(1) Contacting the detergent alkylate with a sufficient amount of a halogenating agent in order to cause nuclear halogenation of the C H hydrocarbon compounds present in said detergent alkylate; and

(2) Separating the nuclear halogenated C H hydrocarbon compounds from the detergent alkylate to recover a detergent alkylate substantially free of the C H hydrocarbon compounds.

OBJECT OF THE INVENTION An object of this invention is to provide a method for selectively removing C H hydrocarbon compounds, such as 1,2,3,4-tetrahydronaphthalenes, 2,3-dihydroindenes, and phenol substituted olefins, from detergent alkylates.

Another object of the invention is to provide a method for selectively removing C H hydrocarbon compounds which is effective, economical, and which does not require the consumption of undesirable amounts of the detergent alkylate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In selectively removing hydrocarbon compounds having the general formula C H where n is an integer from 10 to 24, from a detergent alkylate, I have now found that the C H hydrocarbon compounds undergo nuclear halogenation at a faster rate than the detergent alkylate. Thus, by utilizing up to about 25 mole percent of halogenating agent, based on the total weight percent of the detergent alkylate, the C H hydrocarbon compounds can readily be halogenated and subsequently removed from the detergent alkylate Without appreciable loss of the detergent alkylate by distillation and the like. Such is possible because by halogenating the nuclear portion of the C H hydrocarbon compounds, the boiling points of such compounds and the detergent alkylate are sutficiently separated and one can readily distill the halogenated C H hydrocarbon compounds from the detergent alkylate.

Hydrocarbon compounds which can be readily removed by the process of the present invention and which have the general formula C H where n is an integer from 10 to 24, are generally compounds such as the 1,2,3,4- tetrahydronaphthalenes, 2,3-dihydroindenes, and phenyl substituted olefins. Thus, the following examples are hydrocarbon compounds which are represented by the general formula C H and can be readily removed by the process of the present invention. Such compounds are as follows: 1,2,3,4-tetrahydronaphthalene l-methyl-1,2,3,4-tetrahydronaphthalene 6-ethyl-1,2,3,4-tetrahydronaphthalene l-propyl-3-ethyl-2,3-dihydroindene 1 ,4-diethyl-1,2,3,4-tetrahydronaphthalene 2-phenyl-1-nonene 1,2,3,4,5,6-hexamethyl-2,3-dihydroindene 1,2,3 ,4,5-pentamethyl- 1 ,2,3,4-tetrahydronaphthalene l-methyl-4-heptyl-1,2,3,4-tetrahydronaphthalene 1-ethyl-4-heptyll ,2, 3,4-tetrahydronaphthalene 2-isopropyl-3-tertiary butyl-4-ethyl-5-methyll,2,3,4-tetrahyd ronaphthalene 1butyl-4-decyl-1,2,3,4-tetrahydronaphthalene l-pentyl-3-decyl-2,3-dihydroindene 5 -phenyl-3 ,7-diethyl-4-tetradecene.

The above examples of the various types of C H hydrocarbon compounds are for illustrative purposes only and it is to be understood that the hydrocarbon compounds desired to be selectively removed from detergent alkylates by the present invention can encompass essentially any and all of the possible compounds which fall within the general formula C H The C H hydrocarbon compounds can be removed from the detergent alkylate by the method of a present invention because the C H hydrocarbon compounds are halogenated at a faster rate than the detergent alkylate. Thus, when a crude detergent alkylate containing C H hydrocarbon compound, where n is an integer from 10 to 24, are treated with up to about 25 mole percent of halogenating agent, based on the rate of the detergent alkylate, under halogenating conditions sufficient to convert the C H hydrocarbon compounds to their nuclear halogenated hydrocarbon compound derivatives, the nuclear halogenated hydrocarbon derivatives can be readily separated from the detergent alkylate by simple distillation because of the difference in the boiling points of the detergent alkylate and the halogenated compounds. However, care should be exercised in controlling the amount of halogenation of the C H hydrocarbon compounds so that halogenation of the detergent alkylate is kept at a minimum and thereby allow one to readily separate the halogenated C H hydrocarbon compounds from the detergent alkylate. It has been determined that no more than about 25 mole percent of the halogenating agent, based on the total weight of the detergent alkylate, should be employed in the halogenation of the C H hydrocarbon compounds to prevent an excessive loss of the detergent alkylate.

However, one should recognize that the amount of halogenating agent employed will vary depending upon the level of the C H hydrocarbon compounds present in the detergent alkylate, the level to which the C H hydrocarbon compounds is to be lowered, and the particular system employed for halogenating the C H hydrocarbon compounds. In the halogenation of the C H hydrocarbon compounds, either conventional liquid or vapor phase halogenation of the C H hydrocarbon compounds can be employed. The only criteria is that the halogenation must be conducted under such conditions that the nuclear portion of the C H hydrocarbon compounds are halogenated so that the halogenated C H hydrocarbon compounds can be separated from the detergent alkylate. Because the nuclear portion of the C H hydrocarbon compounds is to be halogenated it is necessary that the reaction be conducted in the absence of light so that the selective nuclear halogenation of the C H hydrocarbon compounds can proceed.

As previously stated, any conventional means for halogenating the nuclear portion of the C H hydrocarbon compounds can be employed. However, regardless of which of the particular halogenation techniques is employed, it is necessary that the degree of halogenation not exceed about 25 mole percent, based upon the total weight of the detergent alkylate present, in order to obtain satisfactory selectivity of the nuclear-halogenated derivatives. Preferably, the halogenation of the C H type hydrocarbon compounds is carried out at a temperature within the range of about C. to about 50 C. in the presence of from about 0.01 to about Weight percent of a halogen carrier catalyst, and more preferably at a temperature within the range of about 2 C. to about 30 C. in the presence of from about 0.01 to about 2 weight percent catalyst.

Any suitable type of halogen carrier catalyst can be employed in the present invention, and such halogen carrier catalyst is especially desirable when operating at the low temperatures specified above. Suitable types of halogen carrier catalysts are iron powder, metallic halides, hydrochloric acid, iodine, and the carboxylic acids. The

metallic halides, which are particularly suited for use as halogen carrier catalyst in the practice of the present invention are the metallic chlorides, such as ferric chloride, zinc chloride, and aluminum chloride. Likewise, suitable carboxylic acids are acetic acid, propionic acid, and formic acid.

When conducting the process of the present invention, the use of a diluent, or solvent, may be desirable. The use of a solvent is not necessary but is preferred when employing a halogen carrier catalyst since the solvent serves to disperse the catalyst component and increase the fluidity of the reaction medium. The solvent can be any liquid of suitable boiling point which is a solvent for the detergent alkylate and which is inert to the catalyst and the detergent alkylate. The term inert liquid as used in the present application is used to mean any liquid which does not react chemically with the detergent alkylate or the catalyst to form undesirable reaction products under the conditions in which the solvent is employed. The amount of solvent which is used depends upon the degree of fluidity desired.

Usually, it is desirable to use from about 200 to 1100 weight percent of the inert solvent based upon the weight of the detergent alkylate. When employing the inert solvent, the detergent alkylate containing the C H type hydrocarbon compounds is mixed with the inert solvent prior to treating same with the halogenating agent. As previously mentioned, any suitable solvent which is inert to the detergent alkylate under the conditions employed in the halogenation of the C l-I type hydrocarbon compounds present in the detergent alkylate can be employed. Suitable solvents are carbon tetrachloride, chloroform, methylene chloride, 1,2-dichloroethylene, ethyl ether, dimethyl formamide, and the like. Especially desirable results had been obtained wherein a chlorocarbon solvent is employed, e.g. carbon tetrachloride.

The halogenating agent employed in the process of the present invention can be chlorine, bromine, or iodine monochloride. However, I prefer to employ either chlorine or bromine as the halogenating agent in practicing the process of the present invention.

In the case of the unsaturated alkylbenzenes of which two were mentioned specifically, i.e. Z-phenyl-l-nonene and 5-phenyl-3,7-diethyl-4-tetradecene, reaction by chlorine at the aliphatic double bond will occur concurrently with the substitution reaction. Also it is possible that the hydrogen chloride present will .add across the double bond. These reactions are evident to those skilled in the art. This added reaction site assures their halogenation and their subsequent removal by distillation.

Once the C H type hydrocarbon compounds present in the crude detergent alkylate have been halogenated in the presence of a halogenating agent, a catalyst, and a solvent, when desired the nuclear halogenated C H- type hydrocarbons can readily be separated from the detergent alkylate. As is evident to those skilled in the art, a minor portion of detergent alkylate will be lost due to some halogenation of the detergent alkylate. However, I have found that when employing no more than 25 mole percent of halogenating agent in the halogenation process no more than about 12 percent detergent alkylate will be lost and, at the same time, one can remove about 35 to percent of the C H hydrocarbon compounds present in the detergent alkylate, thus providing a purified detergent alkylate.

The separating of the nuclear halogenated C H- hydrocarbon compounds from the detergent alkylate can be by any means which are well known in the art. However, due to the difference in the boiling points of the nuclear halogenated C H hydrocarbon compounds and the detergent alkylates, the use of distillation is especially desirable because of the ease of removing the nuclear halogenated C H hydrocarbon compounds from the detergent alkylate. Desirable results have been obtained wherein the vessel Containing the reaction product of the nuclear halogenated C H type hydrocarbon compounds and the detergent alkylate was purged with an inert gas, such as nitrogen, subsequent to the halogenation of the C H hydrocarbon compounds in order to remove any unreacted halogen gas which may be present in the detergent alkylate. Once the vessel containing the mixture has been purged, the detergent alkylate is contacted With a suflicient amount of a mild aqueous-alkali solution to neutralize the treated solution. The neutralized treated solution is then washed with distilled water and dried to remove any trace of the water which may be present in the detergent alkylate. The dried detergent alkylate containing the nuclear halogenated C H hydrocarbon compounds was then distilled thus separating the nuclear halogenated C H type hydrocarbon compounds and any detergent alkylate which may have been halogenated during the process of the halogenation of the C H hydrocarbon compounds, thus allowing one to recover a purified detergent alkylate. Any suitable, mild aqueousfritted disc at the bottom of the cylinder served for entrance of the chloride gas. The cylinder and the condenser were both painted black so as to prevent chlorination of the branch chain and thus obtain nuclear chlorination of the C H hydrocarbon compounds. Runs were then conducted wherein the chlorine was added in the presence of a halogen carrier catalyst and various solvents. In each case where a catalyst was employed, the catalyst was iodine or ferric chloride. After chlorine gas had been injected into the samples of detergent alkylate, nitrogen gas was introduced into the mixture to remove any unreacted chlorine gas. The resulting mixture was then neutralized with a 5 ercent NaHCO solution, washed twice with distilled water, and then dried with anhydrous sodium sulfate. The dried mixture was separated by fractional distillation to determine the amount of C H compounds remaining after distillation. The results of these runs and the conditions of the various runs are shown in the table below.

'IABLESELECTIVE NUCLEAR CHLORINATION F CuH2n8 HYDROCARBON COMPOUNDS CnHZn-B Hydrocarbon Compounds l Determined by mass spectrometry. 2 Determined by gas-liquld-partition chromatography.

alkali solution can be employed in the neutralization of the reaction mixture containing the detergent alkylate and the nuclear halogenated C H hydrocarbon compounds. However, desirable results have been obtained wherein the aqueous-alkali solution employed in the neutralization step is an aqueous sodium bicarbonate solution containing from about 5 to weight percent sodium bicarbonate.

Thus, while the nuclear halogenated C H hydrocarbon compound can readily be separated from the detergent alkylate by distillation, it is to be understood that any other suitable means can be employed. The only criterion is that in order to obtain the desired selectivity the halogenation must occur on the nuclear portion of the C H hydrocarbon compounds so that he halogenated C H hydrocarbon compounds can be separated from the detergent alkylate.

In order to illustrate further to those skilled in the art the nature of the present invention and how it can be practiced the following example is given. As indicated, the example is set forth primarily for the purpose of illustration and, accordingly, any enumeration of details contained therein should not be interpreted as a limitation on the invention except as such are expressed in the appended claims.

EXAMPLE Samples of crude detergent alkylate reaction product mixture obtained by the aluminum chloride catalyzed alkylation of benzene with partially chlorinated C normal paraffins as per US. Patent No. 3,316,294 (1967) were mixed with additional -C,,H hydrocarbon compounds having a molecular weight of 244 so as to provide mixtures containing varying amounts of C H hydrocarbon compounds. The C H hydrocarbon compounds added to the samples of crude detergent alkylate reaction product mixture were obtained by careful, exten sive distillation of a similar crude detergent alkylate reaction product mixture. The mixture was then charged to an upright cylinder which was fitted with a condenser. A

The results from the table above clearly illustrate that when employing the method of the present invention that the C H hydrocarbon compounds can be selectively halogenated and thus removed from the detergent alkylate without a major loss of the detergent alkylate. Further, the above data clearly illustrates that the use of a halogen carrier catalyst and a solvent are not absolutely essential although they are preferred because at the lower temperatures the nuclear halogenation is very slow without the aid of a catalyst and a solvent. Therefore, when operating at a temperature in the range of from about 0 to degrees, preferably from about 2 to 30 degrees, it is preferable to use catalyst and a solvent to selectively halogenate the nuclear portion of the C H hydrocarbon compounds.

The foregoing discussion and description has been made in connection with preferred specific embodiments of the method for selectively removing C H hydrocarbon compounds from a detergent alkylate. However, it is to be understood that the discussion and description is only intended to illustrate and teach those skilled in the art how to practice the invention, and such is not to unduly limit the scope of the invention, which is to be found in the claims set forth here and after.

Having thus described the invention, I claim:

1. A method for selectively removing hydrocarbon compounds having the general formula C H where n is an integer from 10 to 24, from a detergent alkylate comprising:

(a) treating said detergent alkylate with up to about 25 mole percent of a halogenating agent under halogenating conditions sufficient to convert said hydrocarbon compound to nuclear halogenated hydrocarbon compounds, and

(b) separating said nuclear halogenated hydrocarbon compounds from said detergent alkylate.

2. The method of claim 1 wherein said halogenating agent is selected from the group consisting of chlorine and bromine, said halogenation is carried out at a tem perature within the range of about 0 to about 50 C.

in the presence of from about 0.01 to about weight percent of a halogen carrier catalyst, and wherein the halogenation of said hydrocarbon compounds is carried out in the absence of light.

3. The method of claim 2 wherein said halogen carrier catalyst is selected from the group consisting of iodine, iron powder, metallic chlorides, hydrochloric acid and carboxylic acids.

4. The method of claim 3 wherein said metallic chlorides are selected from the group consisting of ferric chloride, zinc chloride, and aluminum chloride.

5. The method of claim 3 wherein said carboxylic acids are selected from the group consisting of acetic acid,

propionic acid, and formic acid.

6. The method of claim 4 wherein said halogen carrier catalyst and said detergent alkylate containing said C H type hydrocarbon compounds are admixed with from about 200 to about 1100 weight percent of an inert hydrocarbon solvent based on the weight of said detergent alkylate prior to treating same with said halogenating agent.

7. The method according to claim 6 wherein said hydrocarbon solvent is a halogen substituted hydrocarbon selected from the group consisting of carbon tetrachloride, chloroform, methylene chloride and 1,2-dichloroethylene.

8. The method according to claim 7 wherein said halogenating'agent is chlorine, said halogen carrier catalyst is iodine and is present in an amount in the range of about 0.01 to 2 weight percent, said hydrocarbon solvent is carbon tetrachloride, and said halogenation is carried out at a temperature within the range of about 2 C. to about C.

9. The method of claim 8 wherein said separating comprises purging the treated material of step (a) with an inert gas to remove unreacted halogenating agent gas, contacting said treated material with a sufiicient amount of an aqueous-alkali solution to neutralize said treated material, Washing the resulting neutralized treated mixture with water, drying the washed material and distilling the washed material to recover a purified detergent alkylate.

10. The method of claim 9 wherein said aqueous-alkali solution is an aqueous sodium bicarbonate solution containing from about 5 to 25 weight percent sodium bicarbonate.

References Cited UNITED STATES PATENTS 2,889,382 6/1959 Wohlers 260-674 3,358,046 12/1967 Ofienhauer et al. 2'60 671 XR 3,423,478 l/l969 Zorn et a1 2 '-650 XR DELBERT E. GANTZ, Primary Examiner C. R. DAVIS, Assistant Examiner US. Cl. X.R. 260650, 671 

